On 05/21/2012 09:45 PM, Rajendra Nayak wrote:> Hi Ben,>> On Monday 21 May 2012 03:17 PM, Ben Dooks wrote:>> On 17/05/12 11:22, Rajendra Nayak wrote:>>> Some divider clks do not have any obvious relationship>>> between the divider and the value programmed in the>>> register. For instance, say a value of 1 could signify divide>>> by 6 and a value of 2 could signify divide by 4 etc.>>> Also there are dividers where not all values possible>>> based on the bitfield width are valid. For instance>>> a 3 bit wide bitfield can be used to program a value>>> from 0 to 7. However its possible that only 0 to 4>>> are valid values.>>>>>> All these cases need the platform code to pass a simple>>> table of divider/value tuple, so the framework knows>>> the exact value to be written based on the divider>>> calculation and can also do better error checking.>>>>>> This patch adds support for such rate table based>>> dividers.>>>> I was considering the idea that you simply pass a>> pointer to a set of routines and a data pointer to>> the clk-divider code so that any new cases don't>> require changing the drivers/clk/clk-divider.c>> I don;t know if I understand your comment completely.> Are you suggesting the get min/max etc be function pointers> passed by platform code (and implemented in platform code?)> so clk-divider does not need an update every time a new divider> type is added?> The idea of extending clk-divider was so its useful for more> than just OMAP, so the code in clk-divider can be reused across> multiple platforms. Did I understand your comment right?>> regards,> Rajendra>>>>> This would make the get max / min / special just>> a function call through a struct.>>>>> Signed-off-by: Rajendra Nayak<rnayak@ti.com>>>> --->>> drivers/clk/clk-divider.c | 67>>> ++++++++++++++++++++++++++++++++++++++++-->>> include/linux/clk-private.h | 3 +->>> include/linux/clk-provider.h | 10 +++++->>> 3 files changed, 75 insertions(+), 5 deletions(-)>>>>>> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c>>> index e548c43..e4911ee 100644>>> --- a/drivers/clk/clk-divider.c>>> +++ b/drivers/clk/clk-divider.c>>> @@ -32,30 +32,69 @@>>> #define div_mask(d) ((1<< (d->width)) - 1)>>> #define is_power_of_two(i) !(i& ~i)>>>>>> +static unsigned int _get_table_maxdiv(const struct clk_div_table>>> *table)>>> +{>>> + unsigned int maxdiv;>>> + const struct clk_div_table *clkt;>>> +>>> + for (clkt = table; clkt->div; clkt++)>>> + if (clkt->div> maxdiv)>>> + maxdiv = clkt->div;>>> + return maxdiv;>>> +}>>> +>>> static unsigned int _get_maxdiv(struct clk_divider *divider)>>> {>>> if (divider->flags& CLK_DIVIDER_ONE_BASED)>>> return div_mask(divider);>>> if (divider->flags& CLK_DIVIDER_POWER_OF_TWO)>>> return 1<< div_mask(divider);

Where are these flags defined? I don't see it in any of the patches in the series. Is my search foo not up to par today?

I think what Ben is saying is that you provider a way (using function or data/table pointers in clk_divider) that will allow the clk provider to define a "divider" to "register value" mapping. Say you decide to do that using a function pointer, then you would implement the following in clk-divider.c.

div_to_reg_one_baseddiv_to_reg_pow_two

The actual clock-provider code will pick one of these or implement their own mapping function. That way, clk-divider won't have to change for any other convoluted variants of clk divider to register value mapping.

-Saravana

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